This invention relates to processes for converting lower aliphatic alcohol, such as methanol, and C4 olefinic hydrocarbons to high octane liquid fuel. In particular, this invention relates to a system for the production of tertiary-butyl ethers in the presence of a lower alkanol, such as methanol, combined with the conversion of olefins to gasoline and a transhydrogenation step to convert branched paraffins to branched olefins for recycle.
There has been considerable development of processes for synthesis of alkyl tertiary-alkyl ethers as octane boosters in place of conventional lead additives in gasoline. The etherification processes for the production of methyl tertiary alkyl ethers, in particular methyl t-butyl ether (MTBE) and t-amyl methyl ether (TAME) have been the focus of recent research. It is known that isobutylene and other isoalkenes produced by hydrocarbon cracking may be reacted with methanol, ethanol, isopropanol and other lower aliphatic primary and secondary alcohols over an acidic catalyst to provide tertiary ethers. Methanol is considered the most important C.sub.1 -C.sub.4 oxygenate feedstock because of its widespread availability and low cost. Therefore, primary emphasis herein is placed on MTBE.
It is an object of the present invention to provide an improved process for the production of C5+alkyl t-butyl ether from isoalkene-rich hydrocarbons, especially MTBE manufacture. It is another object of the present invention to provide an integrated process and reactor system for production of liquid fuel components from C4 aliphatic hydrocarbons incorporating etherification with alkanol and transfer dehydrogenation of paraffins, especially isobutane.